Soil resource heterogeneity in the form of aggregated litter alters maize productivity
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Soils are spatially heterogeneous. To better understand the effects of sub-plant scale soil resource heterogeneity on primary productivity we aggregated plant litter (Trifolium pratense L. shoots and Secale cereale L. leaves) into 8, 24, 32, and 72 patches and uniformly distributed in 50-L containers (0.15 m2) of soil and grew Zea mays L. throughout two seasons. On average aggregated T. pratense litter enhanced final aboveground maize biomass by 14% relative to uniformly distributed T. pratense litter. This effect may be related to the reduction in root carbon allocation observed as lower apparent root respiration rates compared to uniform litter distribution. In contrast, the spatial distribution of S. cereale litter did not affect productivity. The common experimental approach of uniformly distributing resources to understand their influence on soil-plant processes likely oversimplifies field conditions because our results indicate that the spatial distribution of plant litter alone can influence productivity and plant carbon allocation.
KeywordsSpatial heterogeneity Root foraging Nitrogen mineralization Root respiration Soil surface CO2 flux Corn
We are thankful for field and laboratory assistance from G. Parker, J. Simmons, S. Parr, A. Corbin, J. Rensch, B. Rensch, S. Seehaver, M. Gorentz, C. Smart, S. Bohm, S. Vanderwulp, W. Mahaney, T. Robinson, K. Smemo, A. Burgin, M. B. Demming, A. Grandy, and C. McSwiney. For comments on this manuscript we thank, K. Gross, M. Klug, S. Snapp, and two anonymous reviewers. Support for the research was provide by NSF (LTER and DDIG programs), USDA-CSREES (Sustainable Agriculture), and the Michigan Agricultural Experiment Station.
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